In recent years, a personal authentication technique utilizing iris images has been started to be used for entrance/exit management in a restricted building, bank ATMs (Automated Teller Machines), PC login applications, and the like. Especially, the method disclosed in Patent Document 1 has already gone commercial in all over the world and is becoming a de facto standard method.
In the method disclosed in Patent Document 1, an iris region is cut out from an image obtained by shooting the iris, the iris region is expressed in a polar coordinate, and then, 2D Gobor Wavelet filtering is performed to generate an iris code. Then, personal authentication is performed by comparing the thus generated iris code with an iris code registered in advance.
In personal authentication using iris images, there is a possibility of false authentication of a photograph of an iris or a counterfeit eye. Techniques for preventing such false authentication are disclosed in Patent Documents 2 and 3. In Patent Document 2, blinking of an eye or change in pupil diameter is detected. In Patent Document 3, change in pupil diameter is observed while applying stimulation by visible light.
(Patent Document 1) Japanese Patent No. 3307936B
(Patent Document 2) Japanese Patent Application Laid Open Publication No. 2000-105830A
(Patent Document 3) Japanese Patent No. 3315648B